[time-nuts] Fwd: HP5061B Versus HP5071 Cesium Line Frequencies

[Poul-Henning Kamp]

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In message <CABXq0ZCZLhBjpZwt+JTXTgR+xGPraO9x9ewKWXs+JAYe2h87Sw at mail.gmail.com>
, "Donald E. Pauly" writes:

>Electronic thermal coolers did not exist then 

http://www.thermoelectrics.caltech.edu/thermoelectrics/history.html

>Electronic temperature sensors did not exist either.

https://en.wikipedia.org/wiki/Resistance_thermometer#History

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